Measuring apparatus and measuring method

Abstract

Provided is a measuring apparatus including: a light source unit to emit pulsed laser light used for pump light and Stokes light that excite a molecular vibration of a sample; a Stokes light generating unit to modulate an intensity of the pulsed laser light and to generate Stokes light using the pulsed laser light having the modulated intensity; a time delaying unit to delay the pump light using the pulsed laser light or the Stokes light; a detecting unit to detect, by lock-in detection, light transmitted through the sample irradiated with the pump light and the Stokes light having a controlled time delay amount, or reflected light from the sample; and an arithmetic processing device to perform arithmetic processing on the basis of anti-Stokes light detected by the lock-in detection while controlling the intensity modulation and the time delay amount.

1 . A measuring apparatus comprising:
 a light source unit configured to emit pulsed laser light used for pump light and Stokes light that excite a predetermined molecular vibration of a measurement sample;   a Stokes light generating unit configured to modulate an intensity of the pulsed laser light generated by the light source unit with a predetermined reference frequency and to generate Stokes light having a predetermined wavelength using the pulsed laser light having the modulated intensity;   a time delaying unit configured to delay, by a predetermined time, the pump light using the pulsed laser light generated by the light source unit or the Stokes light generated by the Stokes light generating unit;   a detecting unit configured to detect, by lock-in detection, transmitted light that has been transmitted through the measurement sample irradiated with the pump light and the Stokes light having a controlled time delay amount, or reflected light from the measurement sample; and   an arithmetic processing device configured to perform predetermined arithmetic processing on the basis of anti-Stokes light that is detected by lock-in detection by the detecting unit while controlling the intensity modulation in the Stokes light generating unit and the time delay amount in the time delaying unit,   wherein the Stokes light generating unit transmits the pulsed laser light having the modulated intensity through a non-linear optical fiber to generate and set, as the Stokes light, an optical soliton pulse having a wavelength corresponding to the intensity of the pulsed laser light that is to be incident on the non-linear optical fiber, and   wherein the time delaying unit delays the time of the pump light or the Stokes light in accordance with a center wavelength of the optical soliton pulse.   
     
     
         2 . The measuring apparatus according to  claim 1 ,
 wherein the arithmetic processing device controls the intensity of the pulsed laser light to be incident on the non-linear optical fiber and the time delay amount on the basis of a model calculation result or a predetermined database.   
     
     
         3 . The measuring apparatus according to  claim 2 ,
 wherein the arithmetic processing device changes the intensity of the pulsed laser light to be incident on the non-linear optical fiber to sweep a wavelength of the Stokes light within a predetermined wavelength region.   
     
     
         4 . The measuring apparatus according to  claim 2 ,
 wherein the arithmetic processing device fixes the intensity of the pulsed laser light to be incident on the non-linear optical fiber to a predetermined intensity to generate the Stokes light having a predetermined wavelength.   
     
     
         5 . The measuring apparatus according to  claim 2 ,
 wherein, in the arithmetic processing device, the Stokes light having two or more wavelengths is set as the Stokes light having a predetermined wavelength, and   wherein the arithmetic processing device   calculates an intensity ratio of the anti-Stokes light between two or more mutually different molecular vibration modes in the measurement sample from the Stokes light having two or more wavelengths and the pump light, and   generates an image contrast image using the calculated intensity ratio.   
     
     
         6 . The measuring apparatus according to  claim 2 ,
 wherein the Stokes light generating unit includes a light modulation unit in which a rotation-type neutral density filter for wavelength sweeping including a pattern in which concentration changes continuously and a rotation-type neutral density filter for frequency modulation including a shading pattern for frequency modulation rotate by mutually different numbers of rotation, and in which the neutral density filter for wavelength sweeping and the neutral density filter for frequency modulation are configured continuously.   
     
     
         7 . The measuring apparatus according to  claim 2 ,
 wherein the Stokes light generating unit includes a rotation-type neutral density filter that is used for frequency modulation and that includes a shading pattern in which concentration changes continuously.   
     
     
         8 . The measuring apparatus according to  claim 2 ,
 wherein the Stokes light generating unit includes an acousto-optic modulator or an electro-optic modulator and performs the intensity modulation with the acousto-optic modulator or the electro-optic modulator, and   wherein the arithmetic processing device controls the reference frequency to 100 kHz or more.   
     
     
         9 . A measuring method comprising:
 emitting pulsed laser light used for pump light and Stokes light that excite a predetermined molecular vibration of a measurement sample;   modulating an intensity of the generated pulsed laser light with a predetermined reference frequency and generating Stokes light having a predetermined wavelength using the pulsed laser light having the modulated intensity;   delaying, by a predetermined time, the pump light using the generated pulsed laser light or the generated Stokes light;   detecting, by lock-in detection, transmitted light that has been transmitted through the measurement sample irradiated with the pump light and the Stokes light having a controlled time delay amount, or reflected light from the measurement sample; and   performing predetermined arithmetic processing on the basis of anti-Stokes light that is detected by lock-in detection by the detecting unit while controlling the intensity modulation when generating the Stokes light and the time delay amount when delaying the time,   wherein, in generating the Stokes light, by transmitting the pulsed laser light having the modulated intensity through a non-linear optical fiber, an optical soliton pulse having a wavelength corresponding to the intensity of the pulsed laser light that is to be incident on the non-linear optical fiber is generated and set as the Stokes light, and   wherein the time of the pump light or the Stokes light is delayed in accordance with a center wavelength of the optical soliton pulse.